1. Field of the Invention
The present invention relates to a pump apparatus, which is capable of discharging a fluid continuously at a constant rate through a displacement mechanism under a driving operation of a driving element.
2. Description of the Related Art
Heretofore, a constant rate ejection pump has been adopted for supplying a medicinal, a coating, a cleaning solution or the like at a constant rate in a manufacturing apparatus of a semiconductor or the like, a coating apparatus, a medical device, etc.
The present applicant, as disclosed in Japanese Laid-Open Patent Publication No. 2006-029302, has proposed a pump apparatus in which a pump chamber is formed in the interior of a body having a suction port through which a fluid is drawn in and a discharge port through which the fluid is discharged. A piston is displaced along a first chamber inside the body under the action of a pilot pressure. Together therewith, an indirect medium formed from an incompressible fluid is pressed by the piston, and a diaphragm, which is disposed alongside the indirect medium, is flexed, whereupon the fluid filled in the pump chamber is pressed on by the diaphragm and discharged.